Method of separating volatile constituents.



E. 0. BARSTOW & T. GRISWOLD, Jn. METHOD OF'SEPARATING voLA'TlLE CONSTITUENTS,

APPLICATION FILED'DEC. 21. 1914.

1,261,005. Patented Apr; 2,1918.

onnion.

METHOD OF SEPARA'IIN G VOLATILE CONSTITUENTS.

Specification of Letters Patent.

Patented Apr. 2, rate.

Original application tiled October 9, 1912, Serial No. 724,785. Divided and this application flled December To all whom it may coat-em:

Be it known that we, EDWIN O. BARs'row' and THOMAS GRIswoLD, Jr., citizens of the United States, and residents of Midland, county of Midland, State of Michigan, have jointly invented a new and useful Improvement in Methods of Separating Volatile Constituents, of which the following is a specification, the principle of the invention being herein explained and the best. mode in which we have contemplated applying that a principle,- so as to distinguish it from other inventions.

- The present improved method of separatging volatile constituents relates to the removal of such constituents from either liquid or solid materials by means of steam or other condensable vapor, a continuous process of working being preferably employed. Thus the present method finds one field of use in connection with a continuous process of extracting oils and the like, such as shown and described in our co-pending application filed October 9, 1912, Serial "an approximately continuous current into,

through and out of a contact chamber into which steam or other suitable vapor is introduced a like continuous current, near or at the point where the material leaves the chamber. By structural means suited tothe case, this current of steam is caused to flow in a direction opposite to that of the material and to pass through, mix with or contact with it in the chamber, and to finally issue at a pointnear or at the entrance of the current of material into the contact chamber.

.Jlhe effect of the contact of such oppositely-moving currents is to vaporize the solvent and in so doing to condense an equivalent of steam. The vaporized solvent mixes and fiows on with the remaining uncondensed steam, while the steam is condensed in contact with the material in raisingits temperature and evaporating the volatile constituent and flows back with the nonvolatile. ".lhe two oppositely-moving currents of material and vapor, therefore, vary 21, 1914. Serial No. 878,327.

in composition throughout the path of contact. The current of material loses volatile constituents and gains in water of condensation, while the current of vapor gains in volatile constituents and loses in steam. Concurrently with the varying composition of the current of vapor, the vapor temperature will also vary from a high value at point of first contact of the incoming steam with the current of spent material to a low value at the last point of contact of the current of vapor with the incoming current of material. The high value will approximate the temperature of steam at the inlet pressure in the contact chamber and the low value will approach the temperatureof the vapor of the volatile constituent at the exit pressure; which latter will in all cases be plainly'less than the inlet pressure within the contact chamber. Between these high and low values the temperature of the current of vapor will fall as the proportion of steam therein decreases and the low ,value will be lowest when the percentage of vapor of volatile constituent is highest.

Complete removal of uent requires more or less intimate and prolonged contact with the steam, depending on the nature of the material and volatile constituent and the boiling point of the mixture thereof; whereas, economy of steam requires that only enough he used to supply the heat necessary to raise the material to the necessary terminal temperature and to evaporate the volatile constituent at its boilin%point. u

ontrol ofthe steam supply in any given case may be based upon periodical tests of the spent material toascertain the portion,

if any, of volatile constituents remaining therein, and by observation of the proportion of water of condensation (excess steam) coming over from the condenser in which the vaporized volatile constituent 1s recovered. The indications, however, of these periodical tests, or observations of excess condensed steam accompanying the recovered volatile constituent, are far too tardy for practical purposes. 1 In other words,

these tests and observations reflect on con- 105 ditions which may have changed by the time they are made, and hence any such method of control is lacking 1n sensitiveness. In attempting to overcome the difiiculties attendant upon the foregoing method of reguthe volatile constitlation, we have found that if a thermometer be placed in the mixture of vapor of volatile and steam at some point in the path of'the latters contact with the material, the readrow limits.

ing of said thermometer will indicate closely the composition of the vaponat that point, and that consequently variations of such reading will indicate variations in such composition. Hence for any selected point in the path in question there is a critical temperature which, if maintained, will insure the most complete possible removal of volatile with the expenditure of the least possible amount of steam.

We accordingly provide means for varying the steam supply to satisfy the indications of a thermometer placed in the path of contact of the current of material and steam at some point after or later than the first point of contact of the two, in such manner as to keep the temperature reading at the selected point constant within nar- To the accomplishment of the foregoing object, the invention, then, consists of the steps hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth indetail certain steps embodying the invention, such disclosed steps constituting, however, but one of various ways in which the principle of the invention may be used.

In said annexed drawing Figure 1 illustrates our present improved method in diagrammatic fashion; while Fig. 2 illustrates one form of a practical apparatus designed for carrying out the invention in connection with the treatment of solid materials.

In the illustrative apparatusof Fig. 1, the chamber 1 is of course merely typical, the material whether liquid or solid, flowing as indicated by the line 2 from the inlet 3 near the upper end of the chamber to the outlet 4 near the latters lower end. Op-

posed to the current of material is a current of steam 5, which is admitted through inlet pipe 6, near the lower end of the chamber, and passes out, near the latters upper end, by way of'discharge pipe 7. As already explamed the quantity of steam thus discharged is desirably kept at a minimum the vaporized volatile constituting the major portion of the vapor that passes ofi'. Such vapor is thereupon condensed, as in a condenser 8, and the volatilethus recovered.

At a point intermediate of the ends of the chamber 1, is placed a thermometer 9 extendin within said chamber so as to be affecte by the temperature of the oomminglcd steam and vapor therein. mometer obviously serves to indicate temperature at this point and will preferably have a mark 10 indicating what may be termed the critical point for such temperachamber.

Said therwith tlieuse of a minimum amount of steam.

'lhesupply of the latterv is designed to be controlled by a valve 10 in the steam-supply line 6, whereby the operator may regulate the admission of steam in accordance with .variations in the temperature of the current of vapor at the point where the thermometer is located, the object being to keep said thermometer at the temperature 7 indicated by the mark 10 at all times.

The apparatus illustrated in Fig.2 is specifically designed for the treatment of relatively solid material in accordance with the present improved process, such for example as the spent extracted material delivered from an extractor .of the kind illustrated in our co -pending application previously referred to. The material from the extractor proper (not shown) is designed to be delivered to the chamber 52 by a conveyer 51, preferably comprising a tube within which revolves a screw of usual form, such tube extending to the upper end of the chamber. The latter is shown as vertically disposed and forms a heater where the solvent remaining in the material is removed by contact with a counter current of steam. The screw of conveyer 51 stops short of the opening in the steamer chamber, so that such opening is closed by a plug of the moist material which serves to prevent the escape of steam or vaporized solvent from :the

steamer.

Within the steamer chamber are arranged a plurality of shelves 53 which open alternately at the center and periphery of the A central rotatable shaft 54 extends longitudinally of the chamber and carries rakes 55, or like devices, which move over and just above the several shelves, be-

ing adapted to turn over the material on said shelves and to gradually move the same in a spirally inward or outward direction, as the case may be, depending upon whether the shelf opens centrally or at its periphery. The entering material is thus s read out and broken up on the upper shel fed gradually across it, dropped onto the next lower shelf and so on from-shelf toshelf until such material reaches the bottom of the chamber where it is received by the inner end of another screw conveyer 56 that delivers it without the apparatus. The screw in this conveyer, as; in conveyer 51,

stops short of the opening in the conveyer.

pipe so that a portion of the steamed material fillssuch opening and practically seals the steamer against the entrance of air or the escape of vapor.

At the same time that the material is being turned over and raked on the several shelves and gradually fed down through the steamer chamber 52, steam is admitted near the base of the latter by way of pipe 57, such steam rising in a zigzag path in contact with the constantly changing surfaces of the body of material that passes downwardly through the steamer as just described. Any excess of such steam, together with the vaporized solvent, escapes finally through a vapor pipe 58 which carries it to a condenser coil 59 in the tank 60. The action of this opposing current of steam on the material is to thoroughly vaporize the solvent mixed with such material, so that substantially all such solvent is carried off with the steam to this condenser coil. From the latter the condensed steam and solvent are conducted to a suitable separating device. (not shown), 'or otherwise disposed of as seen fit.

In mentioning the excess of steam accompanying the solvent vapors, we wish to point out the fact that the solvent vapor will be greatly in excess and that the steam is present only-in small amount. The amount of steam present will actually be dependent upon whether the .apparatus is being forced or not. If it is being forced, the excess of steam will be great, whereas if it is being Worked at a rate suitable to its capacity, the excess of steam will be quite small.

The supply of steam to the steamer chamber byway of pipe 57 is controlled by a valve 63, which is in turn operated by means of a thermostat 64 mounted at a suitable point in the wall of the chamber 52, so as'to be in contact with the vapor within the latter. Inasmuch as the temperature of such vapor, consisting, as it does, of a mixture of steam and solvent, will vary, depending upon the relative proportions of the two ingredients it follows that there will be a gradual change of temperature within the steamer varying from bottom to top with the different proportions of steam and solvent vapor, and that there will be some certain temperature which, if maintained at the selected point in the vapor space within the steamer chamber, will insure the practically complete absence of solvent or solvent vapor at the base of the steamer. Accordingly, by properly locating the thermostat and adjusting its action, such thermo stat may be adapted to automatically control the steam entering pipe 57, so as to effect a practically complete recovery of the solvent in the material without the waste of steam.

By the foregoing automatically controlled steamsupply valve, we reduce the labor and attention required in the case of the apparatus diagrammatically illustrated in Fig. 1, as well as secure more constant effects. As a further marked advantage, we should note that uneven working, involving either a waste of steam, imperfect separation of volatile, or'both, due to irregularities in-steam pressure available, irregularities of feed of material, or of composition thereof, is efj fectually avoided and uniform results obtained. In other words, complete separation of volatile is obtained with a minimum of' steam.v

Othermodes of. applying the principle of our invention may be employed instead of the one explained, change being made as regards the method herein disclosed, provided the step or steps stated by any one of the following claims or the equivalent of such stated step or steps be employed.

We therefore particularly point out and distinctly claim as our invention 1'. In a method of separating a volatile constituent from a material, the steps which consist in moving such material in contact with a counter current of steam, or the like, whereby a mixture of steam and vaporized volatile is obtained in varying proportions at difi'erent points in the path of such current, and maintaining such mixture at .a" substantially constant temperature at some selected point in such path intermediate between the ends thereof by regulating the supply of steam.

2. In a method of separating a volatile constituent from a material, the steps which consist in moving such material in contact with a counter current of steam, or the like, whereby a mixture of steam and vaporized volatile is obtained in varying proportions at different points in the path of such cur- 100 rent, and maintaining such mixture at a substantially constant temperature at'some selected point in such path intermediate between the ends thereof by automatically regulating the supply of steam by means 105 of a thermostatically controlled steam inlet valve, the sensitive element of the thermostat being placed at such selected point.

3. In a method of separating a volatile constituent from a material, the steps which 11% v consist in moving such material in contact with a counter current of steam, whereby a mixture of steam and vaporized volatile is obtained in varying proportions at dilferent points in the path ofsuch current, and regu- 11h lating the degree to which the volatile in the material is separated therefrom by maintaining such mixture of steam and vapor at substantially a constant temperature at a selected point in such current intermediate x2e between the ends thereof.

4. In a method of removing'the residual solvent from an extracted material, the steps which consist in moving such material against a current of steam, and simulta- I25 neously stirring and turning over such material, the volume of steam being automatically regulated by the temperature of the mixture of steam and vaporized solvent resulting from the action of the steam on the we material at an intermediate point in the course of treatment.

5. In a method of removing the residual solvent from an extracted material, the steps which consist in moving such material in contact dth a counter current of stcann or the like, whereby a mixture of steam and vaporized solvent is obtained in varying proportions at different points in the path of such current, and maintaining such mixture at a substantially constant temperature at some selected point in such path intermediate between the ends thereof by automatically regulating the supply of steam by means of a thermostatically controlled steam inlet valve, the sensitive element of the thermostat being placed at such selected point.

Signed by us, this 18 da-y of December,

EDWIN O, BARSTOW. THOMAS GRISWOLD, JR. Attested by- WM. W. Ross, Jr., NORMAN BEST. 

